1. Technical Field
The present application relates generally to electronic devices including a user interface having a haptic-based touch screen, and particularly to such a device having a prolonged useful life.
2. Description of the Related Art
Electronic devices typically include a user interface with a touch screen in which user selections may be made by making contact with the touch screen. Some electronic devices also provide both audio and tactile feedback in addition to visual feedback as selections are made on the touch screen. Haptics is a newer technology for providing tactile feedback to a user, and in combination with audio and visual feedback creates an enhanced level of usability and customer experience.
In the electronics industry, haptic feedback is generally accomplished by vibrating a liquid crystal display (LCD) and touch panel that are rigidly mounted together as a combined pair. However, vibrations delivered to the LCD have been found to induce premature wear on the LCD, and reduce its overall life. In addition, the force required to vibrate both an LCD and a touch panel of a relatively large size necessitates the use of more expensive linear actuators.
Haptics is typically achieved through any of several different methods. Haptic events are created by using an Eccentric Rotating Mass (ERM) to vibrate the entire device, using one or more piezo strips to isolate the effect two dimensionally, or using linear actuators to vibrate an entire touch surface along a single axis. The existing approaches vibrate the touch panel and the LCD display or in some cases, such as cell phones, the entire electronic device vibrates. These existing approaches suffer from being relatively expensive and/or having other shortcomings.
In the case of the cellular phones, the haptic assembly vibrates not just the touch panel and LCD but the entire phone. Vibration will cause the LCD to fail prematurely. However, since the lifetime of a typical cell phone is short, relative to the life of a standard LCD, this is considered an acceptable tradeoff. Larger scale electronic devices do not have the luxury of such a tradeoff.
In the case of larger touch panel applications, using linear actuation is a more expensive way to implement haptics. The linear actuators are expensive, consume a relatively sizeable amount of power and require a relatively difficult assembly, all of which add to system cost. Electronic devices having larger touch panel and LCD assemblies require a larger linear actuator, thereby further increasing system cost and power consumption.